1.2 Network Models

Question 1

Two most important network models:

Answer 1

1. Open System Interconnection (OSI) model
2. Internet Model

Question 2

Usually called the OSI Model for short

Answer 2

Open Systems Interconnection (OSI) Reference Model

Question 3

Commercial networks used by businesses were built using non-standardized technologies developed by one vendor (sometimes referred to as ____________, or vendor-specific)

Answer 3

proprietary

Question 4

During the late 1970s, the International Organization for Standardization (ISO) created the ________________________ Subcommittee, whose task was to develop a framework of standards for computer to computer communications

Answer 4

Open System Interconnection (OSI)

Question 5

Other characteristics of the OSI model include:
1. OSI model is _____ a protocol
2. It is a model for understanding and designing a ____________ that is flexible, robust, and interoperable

Answer 5

NOT…network architecture

Question 6

It consists of ________ separate layers, each of which defines a part of the process of moving information across a network

Answer 6

seven

Question 7

OSI Model Layers:

Answer 7

1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Data Link
7. Physical

Question 8

The ____________ coordinates the functions required to carry a bit stream over a physical medium or channel.

Answer 8

physical layer

Question 9

It is responsible for moving the individual bits from node (or hop) to the next

Answer 9

Physical Layer

Question 10

It deals with the mechanical and electrical specifications of the interface and transmission medium

Answer 10

Physical Layer

Question 11

It also defines the procedures and functions that physical devices and interfaces must perform for transmission to occur

Answer 11

Physical Layer

Question 12

The ____________ is also concerned with the following:
1. Physical characteristics of the interfaces and medium
2. Representation of bits – defines the type of encoding (how bits are changed to signals)
3. Data Rate
4. Synchronization of bits
5. Line configuration
6. Physical topology
7. Transmission mode

Answer 12

physical layer

Question 13

The ____________ transforms the physical layer to a “reliable link.” It is also responsible for moving frames from one node (or hop) to the next

Answer 13

data link layer

Question 14

Responsibilities of this layer includes:
1. Framing
2. Physical addressing
3. Flow control
4. Error control
5. Access control

Answer 14

Data Link Layer

Question 15

Data link layer divides the stream of bits received from the network layer into manageable data units called frames

Answer 15

Framing

Question 16

Adds a header to the frame to define the sender and/or receiver of the frame

Answer 16

Physical addressing

Question 17

Imposes a flow control mechanism to avoid overwhelming the receiver

Answer 17

Flow control

Question 18

Add mechanisms to detect and retransmit damaged or lost frames

Answer 18

Error control

Question 19

When two or more devices are connected to the same link, this layer determines which device has control over the link

Answer 19

Access control

Question 20

The ____________ is responsible for the source-to-destination delivery of a packet, possibly across multiple networks (links)

Answer 20

network layer

Question 21

Oversees the delivery of the packet between two systems on the same network

Answer 21

Data link layer

Question 22

Ensures that each packet gets from its point of origin to its final destination

Answer 22

Network layer

Question 23

Other responsibilities of the network layer include:

Answer 23

1. Logical addressing
2. Routing

Question 24

Adds header to the packet, including the logical address (address needed to help distinguish the source/destination systems)

Answer 24

Logical addressing

Question 25

When independent networks or links are connected to create internetworks or a large network, the connecting devices (called routers or switch) route or switch the packets to their final destination

Answer 25

Routing

Question 26

The ____________ is responsible for process-to-process delivery of the entire message

Answer 26

transport layer

Question 27

A __________ is an application program running on a host

Answer 27

process

Question 28

Computers often run several programs at the same time --- therefore, source-to-destination delivery means not only from one computer to the next but also from a ____________

Answer 28

specific process

Question 29

To do this, a type of address called ____________ (or port address) is included in the transport layer header

Answer 29

service-point address

Question 30

Other responsibilities of the transport layer include:

Answer 30

1. Segmentation and reassembly 2. Connection control 3. Flow control 4. Error control

Question 31

A message is divided into transmittable segments, with each segment containing a sequence number

Answer 31

Segmentation and reassembly

Question 32

Treats each segment as an independent packet and delivers it to the transport layer at the destination

Answer 32

Connectionless

Question 33

Makes a connection with the transport layer at the destination machine first before delivering the packets

Answer 33

Connection-oriented

Question 34

Flow control at this layer is performed end to end rather than across a single link (which is done by the data link)

Answer 34

Flow control (transport layer)

Question 35

Performed process-to-process rather than across a single link

Answer 35

Error control (transport layer)

Question 36

The ____________ is the network dialogue controller --- it establishes, maintains, and synchronizes the interaction among communicating systems

Answer 36

session layer

Question 37

Specific responsibilities of the session layer include:

Answer 37

1. Dialog control 2. Synchronization

Question 38

Session layer allows two systems to enter into a dialog; it allows the communication between two processes to take place in either half-duplex or full-duplex

Answer 38

Dialog control

Question 39

The session layer allows a process to add checkpoints or synchronization points (or bits) to a stream of data

Answer 39

Synchronization

Question 40

The ____________ is concerned with the syntax and semantics of the information exchanged between two systems

Answer 40

presentation layer

Question 41

Specific responsibilities of the presentation layer include:

Answer 41

1. Translation 2. Encryption 3. Compression

Question 42

Because different systems use different encoding techniques, this layer is responsible for interoperability between these encoding methods

Answer 42

Translation

Question 43

Means that the sender transforms the original information to another form

Answer 43

Encryption

Question 44

Data compression reduces the number of bits contained in the information

Answer 44

Compression

Question 45

The ____________ enables the user, whether human or software, to access the network. It is also responsible for providing services to the user

Answer 45

application layer

Question 46

Specific responsibilities of the application layer include:

Answer 46

1. User Interface (UI) 2. Network virtual terminal 3. File transfer, access, and management 4. Mail services 5. Directory services

Question 47

A software version of a physical terminal that allows a user to log on to a remote host

Answer 47

Network virtual terminal

Question 48

Allows a user to access files in a remote host, to retrieve files, and to manage or control files

Answer 48

File transfer, access, and management

Question 49

Provides distributed database sources

Answer 49

Directory services

Question 50

1. Application 2. Transport 3. Network 4. Data Link 5. Physical

Answer 50

The Internet Model layers

Question 51

Google Chrome (browser), Web Pages (through HTTP) are examples of ____________

Answer 51

application layer

Question 52

TCP/IP protocol is an example of ____________

Answer 52

Internetwork or INTERNET layer group (Transport & Network Layer)

Question 53

Ethernet ports, Ethernet cables, and Ethernet software drivers are examples of ____________

Answer 53

Hardware layer group (Data Link & Physical Layer)

Question 54

A set of rules that define what the layer will do and provides a clearly defined set of messages that software at the layer needs to understand

Answer 54

Protocol

Question 55

All layers, except the physical layer, create a new ___________________ as the message passes through them

Answer 55

Protocol Data Unit (PDU)

Question 56

The _______ contains information that is needed to transmit the message through the network

Answer 56

Protocol Data Unit (PDU)

Question 57

First, on the sender's end, a user may create a message at the ___________ layer (e.g., web page request using a browser)

Answer 57

application

Question 58

The transport layer uses the protocol ___________________ to break this request (or other large files) into smaller segments

Answer 58

TCP (Transmission Control Protocol)

Question 59

The network layer then uses the IP (Internet Protocol) to select the next hop or stop on the message's route; PDU is called an ____________

Answer 59

IP packet

Question 60

The data link layer adds start and stop markers, error checks information, and places the packet in a __________ - the PDU at this layer

Answer 60

frame

Question 61

The physical then sends the frame as series of 0s and 1s (or ______) onto the physical channel

Answer 61

bits